Compound resonance unit



Jan. 27, 1942. E. E. WILSON COMPOUND RESONANCE UNIT Original Filed Jan. 30, 1933 2 Sheets-Sheet l lmaen tar w ZM flttorne v S Jan. 27, 1942. E. E. WILSON 2,271,055

COMPOUND RESONANCE UNIT Original Filed Jan. 30, 1933 2 Sheets-Sheet 2 Hum Inventor ,4 orneya Patented Jam 27, 1942 COMPQUND RESONANCE UNIT Ernest E. Wilson, near Milford, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application January 30, 1933, serial No.

1939, Serial No. 281,439

7 Claims. (Cl. 181-40) This application is a division of my application Serial No. 654,296, illed January 30, 1933, on which Patent No. 2,164,365 was issued on July 4, 1939, and, in part, a continuation of my application Serial No. 470,700, filed July 25, 1930.

The invention with which this application is concerned has to do with resonance unitsof the type disclosed in my application Serial No. 470,700. In the main, this application is concerned with certain embodiments or features of the invention disclosed but not specifically claimed in my application Serial No. 470,700, or in my Patent No. 2,164,365, or in my application Serial No. 633,265,

filed September 15, 1932, which is also, in part,

a continuation of application Serial No. 470,700.

For a better understanding of the nature of the invention with which this application is concerned, reference is made to the following spec; ification in which are described the several embodiments of the invention which are illustrated in the accompanying drawings.

In the accompanying drawings:

Figure l is a side elevation of an internal combustion engine equipped with intake and exhaust silencers in which are incorporated resonance units in which the invention with which this application is concerned is embodied.

Figure 2 is a central longitudinal section through the silencer installed on the intake tube 01' the carburetor of the engine illustrated in Figure 1.

Figure 3 is a central longitudinal section through the silencer installed on the exhaust pipe of the engine illustrated in Figure 1.

Figure 4 is a central longitudinal section through a modified form of silencer in which the invention with which this application is concerned is embodied.

In Figures 1, 2 and 3 of the drawings, the reference character l indicates an internal combustion engine which is equipped with a carburetor II which is connected to the cylinders of the engine by a manifold 12 and an exhaust pipe l4 which is connected to the cylinders of the engine by a manifold l5. To the air intake tube 13 of the carburetor and to the exhaust pipe, there are connected silencers l6 and 51, respectively, in which are incorporated resonance units of the type with which this application is concerned.

The silencer l6, which is shown in Figures 1 and 2 of the drawings, includes a cylindrical shell I! over whose ends there are secured heads l3 and [9. The interior of the shell I1 is sub- Divided and this application June 27,

and 2t by an annular partition 22 whose outer edge is circumferentlally secured to the shell- Through the central opening in the partition 22, there extends from the compartment 20 into the compartment 2| 9. tube 23 which is circumferentially secured to the inner edge of the partition 22. To the end of the tube 23 which is located within the compartment 20, there is secured a perforated annular flange 24 whose outer edge is circumferentially secured to the shell ll. In the head [3, there is provided a central opening of larger diameter than that in the partition 22 through which there extends into the shell I! a tube 25 which is of larger diameter than the tube 23 and whose inner end encircles and is circumferentially spaced from the adjacent end of the tube 23.

Through the side wall of the shell ll, there extend into the compartment 20 a ring of openings 26 through which air may pass from the atmosphere into the tube 23. The end walls 18 and 22 of the compartment 20 are lined with bodies of sound absorbing material which are held against the walls by an element 21 and the flanges 24, respectively. Each of the bodies of sound absorbing material preferably consists of a mat of hair felt 28 covered by a layer of burlap or other porous fabric 29 secured to the mat during the felting operation, or by punching, of by an adhesive, but may be constructed of any other suitable material or combinations of materials.

The interior of the compartment 21 is divided into a primary resonance chamber 30 and two secondary resonance chambers 3| and 32 by an annular partition 33 whose outer and inner edges are circumierentially secured to the shell I7 and the tube 23, respectively, and an annular partition 34 whose outer and. inner edges are circumferentially secured to the shell I7 and the tube 25, respectively. Communication between the secondary resonance chambers 3| and 32 and the primary resonance chamber 30 is established by tubes 35 and 36 which extend through openings in, and are circumferentially secured to, the partitions 33 and 34, respectively.

As shown in Figure 1 of the drawings, the silencer i6 is adapted to be installed on the air intake tube of the carburetor of an internal combustion engine by inserting one end of the tube 25 into the carburetor air intake tube and suitably securing it thereto. When the silencer is so installed and the engine is operating, the suction created by the cylinders on their suction divided longitudinally into two compartments 20 strokes, will draw air through the openings 26, into the compartment 28 and, thence, into the tube 28, whence it will pass through the tube 28, the carburetor and the intake manifold into the cylinders of the engine. Since, as is apparent from the drawings, there is an unobstructed path through the silencer into the air intake tube of the carburetor, the silencer will offer practically no resistance to the passage of air therethrough.

The resonance unit (which consists of the resonance chambers 80, 8| and 82, the passages which interconnect them and the passage which interconnects the primary resonance chamber 80 and the main passage 28-28) of the silencer i8 is so proportioned and dimensioned in the manper set forth in my application Serial No. 470,700

and the corresponding foreign patents, viz., Canadian Patent No. 348,037, British Patent No. 391,180, French Patent No. 720,611 and Italian Patent No. 300,037, that it will respond to and attenuate the objectionable sound waves of relatively low frequency which are ordinarily transmitted through the intake manifold and carburetor of the engine to the atmosphere. The obiectionable sound waves of relatively high frequency which are ordinarily transmitted through the intake manifold and carburetor of the engine to the atmosphere are attenuated by the bodies of sound absorbing material with which the compartment 28 is lined. Thus, by their conjoint action, the resonance unit and the sound absorbing material effectually attenuate all of the objectionable sound waves which -are ordinarily transmitted through the intake manifold and carburetor of the engine to the atmosphere and eliminate the so-called intake noises which are ordinarily found in internal combustion engines.

To illustrate some of the many forms which resonance units in which the invention with which this application is concerned is embodied may assume, I have included in the drawings Figures 3 and 4. It is to be understood that the structures illustrated in Figures 3 and 4 of the drawings, as well as those shown in Figures 1 and 2, may be modified in many ways as to details of construction and that modified structural features shown in any of the figures may be incorporated in the resonance units shown in any other or others of the figures.

The resonance unit which is shown in Figure 3 of the drawings includes a shell 60 over whose ends there are secured heads SI and 62. Through the heads and the interior of the shell there extends a tube 88, which through its projecting end 88, is adapted to be connected to the air intake tube of a carburetor so as to form an extension thereof. The space between the shell 88 and the tube 88 is divided by""partitions 85, 88 and 81 into resonance chambers 88, 88, 10 and II of which the resonance chamber 88 is directly connected to the interior of the tube 88 by a tube 12. The resonance chamber 88 is directly connected to the resonance chambers 88, I8 and II by tubes I8, II and I which extend through the partition 08, the partitions 85 and 88 and the partitions 88, 88 and 81, respectively. The resonance chamber 88 is directly connected to the resonance chambers 10 and II by tubes I8 and 11 which extend through the partition 88 and the partitions 88 and 81, respectively. The resonance chamber 10 is directly connected to the resonance chamber 1| by a tube 18 which extends through the partition 81. While the resonance chamber 88 can be considered only as a primary resonance chamber, the resonance chambers 88, Ill and II, by virtue of the fact that each is connected directly to the other and to the primary resonance chamber 88, can be considered as secondary, tertiary or quaternary resonance chambers. In view of what was said in the sentence next preceding this, it will be apparent that the resonance unit shown in Figure 3 is the equivalent of a resonance unit of the type shown in Figure 2 in which the secondary chambers 3i and 82 are directly interconnected and to whichthere has been added a resonance chamber directly connected to each of the chambers 30, 8| and 82. Obviously one or more of the tubes I8, 14, I5, I8, 11 and 18 may be omitted and the characteristics of the resonance unit shown in Figure 3 thus modifled.

The resonance unit which is shown in Figure 4 cf the drawings includes a shell over whose ends there are secured heads and 82. Through the heads and the interior of the shell, there extends a tube 88, which through its projecting end 84, is adapted to be connected to the air intake tube of a carburetor so as to form an ex tension thereof. The space between the shell 88 and the tube 83 is divided by partitions and 88 into resonance chambers 81, 88 and 88 of which the resonance chamber 88 is directly connected to the interior of the tube 88 by a tube 80. Each of the resonance chambers 81 and 88 is directly connected tothe resonance chamber 88, the former by a tube 8| which extends through the partition 88 and the latter by a tube 82 which extends through the partition 86. The resonance chambers 81 and 88 are directly interconnected by a tube 83 which extends through the partitions 85 and 86 and to whose intermediate portion there is connected a tube 84 which extends through the wall of the shell 80 and connects the tube 88 with the atmosphere. While the resonance chamber 88 can be considered only as a primary resonance chamber, the resonance chambers 81 and 88, by virtue of the fact that each is directly connected to the other and to the primary resonance chamber, can be considered as either secondary or tertiary resonance chambers. It will be obvious that the tube 83 and/or the tube 84 may be omitted and that if both are omitted, the resonance unit shown in Figure 4 will be equivalent to a resonance unit of the type shown in Figure 2.

Although the resonance units herein disclosed are particularly adapted for use in attenuating the sound waves which are ordinarily transmitted through the intake manifold and carburetor of an internal combustion engine to the atmosphere, resonance units of the same type may be effectually used to attenuate sound waves in any enclosure of finite dimensions. It will, of course, be understood that, in designing resonance units for use in any installation, it is necessary so to proportion and dimension them in the manner set forth in my application Serial No. 470,700 and the corresponding foreign patents previously referred to that they will respond to the sound waves which they are intended to attenuate.

While it will be understood that effectually to attenuate the sound waves which travel through the exhaust pipe of an internal combustion engine toward the atmosphere, it is generally desirable to employ somewhat differently designed resonance units than are employed on the induction systems of such engines and that, in general, it is preferable to employ for this purpose resonance units, such as are disclosed in my application Serial No. 633,265, in which there are provided a greater number of resonance chambersthan are necessary in resonance units which are designed for use on the induction systems of such engines, I have, for the purpose of indicating the applicability of resonance units of the type with which this application is concerned to the exhaust systems of internal combustion engines, shown in Figure 1 of the drawings the resonance unit 51 which is shown in Figure 3 o! the drawings installed on the exhaust pipe I of the engine III with the projecting end 64 of the tube 63 telescopically connected with the por-- tion of the exhaust pipe which is located on the engine side of the resonance unit.

I claim:

1. In a silencer, a tubular member, another tubular member which encircles and is radially spaced from a portion or the first-specified tubular member and defines with it a duct through which gases travel and into which sound waves enter, a shell which encircles the duct and with it defines a substantially blind compartment, and partitions which encircle, respectively, the second-specified tubular member and the firstspecified tubular member but not the secondspecified tubular member and subdivide the compartment lengthwise into three chambers of which the intermediate chamber communicates with the duct as a side branch through the aperture between the tubular members and the end chambers communicate with the intermediate chamber independently of the duct and each other.

2. The combination, with a passage in which sound waves occur and which includes a conduit and a larger conduit into which the first-mentioned conduit extends, of a casing which surrounds the overlapping portions of the conduits and defines therewith a compartment, partitions, one secured to an end of the larger conduit and to the casing and another to the smaller conduit and the casing subdividing the compartment longitudinally into three chambers of which the intermediate chamber communicates with the pas-' specified chamber independently of the duct and each other and with each other independently of the first-specified chamber.

4. The combination, with a passage or other enclosure within which sound waves occur, of a side branch which includes a compartment which communicates with the enclosure and a plurality of compartments which communicate with the first-mentioned compartment independently of the enclosure and of each other and with each other independently of the first-mentioned com-,

partment and is so proportioned and dimensioned that it responds to and attenuates by resonance objectionable sound waves which occur within the enclosure.

5. In a silencer, a duct through which gases travel and into which sound waves enter, and a substantially blind side branch which includes a-chamber which communicates with the duct, chambers which communicate with the firstspecified chamber independently of the duct and each other, and a chamber with which both of the "second-specified chambers communicate independently of the other and the first-specified chamber.

6. The combination, with a duct through which gases and sound waves travel, of a resonator which is arranged as a branch of the duct and is so tuned that it responds to and attenuates by resonance sound waves of preselected frequencies which travel through the duct, the resonator including a chamber which communicates with the duct, and a plurality of chambers which communicate with the first-specified chamber independently of the duct and each other and with a fourth chamber independently of the first-specified chamber and the duct.

7. In a silencer, a tubular member which constitutes a duct through which gases travel and into which sound waves enter, a shell which encircles the tubular member and with it defines a substantially blind compartment, partitions which subdivide the compartment lengthwise into three chambers, an aperture through which the intermediate chamber communicates with the duct, apertures through which the end chambers communicate with the intermediate chamber independently of the duct and each other, and a duct through which the end chambers communicate with each other independently of the intermediate chamber.

ERNEST E. WILSON. 

